TERA8 THz-Antennas0 pages
THz-ANTENNAS
nnnnFOR 800 nm
nnnnTHE SOLUTION
nnnnFOR FREE-SPACE
nnnnTHz SYSTEMS
nnnnThe Tera8 comprises six dipole struc-
nnnntures on one single chip. With the
nnnn"6 in 1" approach highest bandwidth
nnnnand highest sensitivity on one chip
nnnnbecome reality. Each chip can be
nnnnused as emitter or as detector.
nnnnMake no compromise in performance
nnnnand flexibility!
nnnnWe bring Tera8 to the market with
nnnnour collaborator the IPM, the Fraun-
nnnnhofer Institute for Physical Measure-
nnnnment Techniques IPM.
nnnnFraunhofer
nnnnInstitut
nnnnPhysikalische
nnnnMesstechnik
nnnnFeatures
nnnnPhotoconductive switch optimized for lasers around 800 nm
nnnnand pulse width <150 fs
nnnn6 dipole structures on each chip
nnnnLow temperature (LT) grown GaAs dipole structure
nnnnWe test each device and include the individual test report in the shipment
nnnn— 1
nnnnQ.
nnnnE
nnnn■ i-l—L_J 11 l l l l / 1 Time [ps] \ 15 20 25 30 | ||
Amplitude [a.u.] | ||
I |
Frequency [THz]
nnnnSpectrum of emitted THz radiation (insert shows data plot of electrical field as function of time)
nnnnTest Conditions for Data Plots
nnnnOptical source: fs fiber laser operating at 780 nm and 130 fs pulse width
nnnnData recorded with 20 urn dipole used on emitter and detector side
nnnnMechanical chopper with 1 kHz
nnnnLock-in detection with 30 ms integration time
nnnn10 mW of optical input power at emitter and detector side
nnnnUp to 45 V bias for emitter
nnnnThe THz region of the electromagnetic spectrum lies between the microwave and the infrared part. THz waves are of major
nnnninterest in spectroscopy, quality control and security applications.
nnnnPhotoconductive switches are used as emitters and detectors for THz radiation. Simply illuminate the antenna with femtosecond
nnnnoptical pulses and get THz waves.
nnnnTHz Generation
nnnnA photoconductive antenna, e.g. a low temperature grown GaAs layer with
nnnnmetallic contacts can be used as an optical excited broadband terahertz
nnnnemitter. Typically, an alternating voltage is supplied to the contacts to allow
nnnna lock-in measurement. Two important antenna parameters are the dipole
nnnnlength and the gap distance of the
nnnnantenna structure. The dipole length
nnnndetermines the preferred emitted
nnnnfrequency at the resonance
nnnncondition. Typically, a silicon lens
nnnnaligned with the antenna is used to
nnnnincrease the extraction efficiency for
nnnnthe THz waves.
nnnnTHz Detection
nnnnThe detector has a similar or even exactly same design as the emitter. The
nnnnoptimal gap between the metallic contacts is about equal to the laser spot
nnnndiameter. A current amplifier
nnnnconnected to the detector contacts
nnnndelivers a signal proportional to the
nnnnterahertz electric field strength.
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